• A comma looks like this:

,

• A comma is used to:
• separate elements in a sentence, introductory clause, words in a series, parenthetical phrase, or interjection
• separate items in lists, and to present large numbers in a more readable form
• when using commas in a number in English, the commas are placed before every third digit, starting from the right
• commas can change the meaning of a sentence depending on placement

• Commas in numbers
• "fifteen million" is written as "15,000,000"
• "twelve thousand fifty-one dollars and seven cents" is written as "$12,051.07"
• Commas changing the meaning of a sentence
• "The teacher beat the scholar with a whip." (a simple description)
• "The teacher beat the scholar, with a whip." (expression of outrage)